This invention relates to channel nuts for fastening objects to metal channel framing wherein the nut is positioned crosswise in the channel during securing of the object to the channel.
Metal framing is commonly used for electrical, mechanical and industrial supports such as for lighting fixtures, pipes and so forth. The framing is formed as a channel having side flanges with opposing, inwardly turned, hook shaped lips defining a slot therebetween. An elongated nut which is narrower and longer than the width of the slot is typically used for securing objects to the framing. As such, the nut is first aligned with the framing and then turned crosswise with the nut engaging the lips of the channel. An object such as a bracket for a lighting fixture is then locked into position by means of a bolt extending through the object and threaded into a tapped hole in the nut.
A channel nut typically has an inside face, an outside face, opposite sides and opposite ends. Diagonally opposite corners of the nut are rounded to facilitate installation. A tapped hole for threadably receiving a bolt extends completely through the nut from the outside face to the inside face of the nut. Parallel slots with upstanding teeth extend across the outside face of the nut at opposite sides of the threaded hole for gripping the channel lips. The solid steel channel nuts presently in common use are made in a multistep process from bar stock, sections of which are first perforated with a pilot hole. The section is then coined to form the parallel slots with teeth, tapped to form the threaded hole and diagonal corners rounded off. If a lead in is provided for the bolt, the tapped hole is countersunk on the outside face of the nut. If a clamp is provided for holding the channel nut in its crosswise position prior to and during securement of the object to the channel, the solid steel nut may be further processed. For example, the clamp used in U.S. Pat. No. 4,146,074 requires that the sides of the nut be slotted which dictates a separate broaching step with its attendant costs. The fastener disclosed in U.S. Pat. No. 4,410,298 has no slot but it requires drilling a pair of holes in the inside face of the nut.
Not all applications for channel nuts require the strength provided by a solid steel channel nut. In addition to cost, solid steel channel nuts have other disadvantages, one being that the tapped hole is at the level of the inside faces of the framing when the nut is in crosswise position. Thinner nuts are used for shallow channel, increasing the number of different nuts which have to be stocked, but the minimum depth of the channel is still limited because the bolt must make a necessary number of turns in the nut before it is stopped.